Handheld computing devices or "palmtops" typically weigh less than a pound and fit in a pocket. These palmtops generally provide some combination of personal information management, database functions, word processing and spreadsheets. Users of palmtops may also own personal computers (PCs) running applications that manage data similar to the data carried in the palmtops. In such cases, the user normally would want the data on their palmtop to be easily synchronized with the data on their PC.
A number of programs today transfer data between palmtops and PCs, but they are currently limited in functionality. Some programs transfer all the information from the palmtop to the PC without regard for the prior content on the PC. These programs assume that changes to that particular data are only made on the palmtop, and that the changes made on the palmtop take precedence over any changes made on the PC. As a result, any independent updates made directly on the PC will be lost.
Other methods use `flags` to facilitate synchronization. These methods create update `flags` in each record that has changed, both on the palmtop and the PC. Corresponding files on the palmtop and the PC are then compared, and if one or more flags are set in a file, the file is recognized as having changed. If both the palmtop and PC files have changed, the flags are used to determine which records need to be updated in the other file. The databases of most existing programs, however, do not contain such flags since the databases of most existing programs were not designed to be synchronized. Thus, a different method must be used to synchronize data from programs that are already on the market.
Some programs attempt to synchronize the data on the PC with the palmtop by comparing the information in each application and prompting the user for answers to determine which data to overwrite. For example, U.S. Pat. No. 5,392,390 describes a method for reconciling information between two calendar database files by interrogating the user about which file to update when a difficult case arises. Although these types of programs provide an advantage over programs that assume only one database has changed since they do not indiscriminately overwrite data, they are cumbersome and time consuming. Using these methods, users may have to spend an inordinate amount of time answering questions whenever they attempt to synchronize information between their palmtops and their PCs.